China's top environmental official called for patience with the cleaning up of air pollution in the country, but vowed to solve the problem faster than the time taken by the developed countries.

"The campaign against air pollution cannot be accomplished in a short period of two or three years, and will take a relatively long time," Minister of Environmental Protection Chen Jining said Thursday on the sidelines of the ongoing sessions of the National People's Congress (NPC) in Beijing.

It took 20 to 40 years, or even 50 years, for developed countries to clean up air pollution, but "China will surely be faster than the developed countries in solving this problem," he said.

Chen said that in the past three years, the number of days with good air quality increased in major Chinese metropolitan areas, including the Beijing-Tianjin-Hebei area, the Yangtze River Delta and the Pearl River Delta. The PM2.5 density in these three regions, except Beijing, was reduced by more than 30 percent in 2016 compared with 2013, he said.

"We are facing more difficult conditions in China, such as an energy structure with coal and fossil fuel as the main sources and a fast-growing ownership of vehicles," Chen said, compared with developed countries.

The task of making Beijing's air clean is especially difficult. The density of pollutants in the air is caused by both emissions and climate conditions; pollution from emissions in southern Hebei can reach Beijing in several hours with north-bound winds, and there are 2,370 such sources of emissions in the Beijing-Tianjin-Hebei area, Chen said.

The ministry put in place a special monitoring system for the emissions, and after a year of reporting and punishment, the rate of the emissions exceeding the standard has dropped from 31 percent to 3.8 percent since early 2016.

"The result of environmental protection efforts might be easily affected by meteorological factors over a short period of time, so we need a longer period of three years to tell if the measures are effective," Ma Jun, director of the Institute of Public and Environmental Affairs, a non-profit environmental protection organization based in Beijing, told the Global Times on Thursday.

　　Stricter law enforcement

According to Chen, the Ministry of Environmental Protectionhas found more than 2,000 problems in the previous special inspections on air quality in the Beijing-Tianjin-Hebei area and nearby regions, and the officials would continue to press for strict enforcement to improve environmental conditions.

More than 124,000 administrative penalties have been handed down by different levels of environmental departments, with a combined fine of 6.63 billion yuan ($960 million), in 2016. The fines marked a 56-percent surge from a year earlier, Chen said at the press conference.

China will step up law enforcement to crack down on illegal practices, Chen said, promising "zero tolerance" for such offenses.

In 2017, the ministry will carry out inspections in another 15 provincial regions to check their pollution control efforts.

China's revised Environmental Protection Law took effect in January 2015. The law is considered to be the strictest ever, stipulating harsh punishments for polluters and highlighting the government's duties.

"But after two years, there are some outstanding issues in implementation that need to be studied and solved," Chen said on Thursday.

Some systems and policies in environmental protection are still not complete, and the duties are not clear for some departments.

A number of government departments are involved in the cause of environmental protection. "For instance, the Ministry of Environmental Protection is in charge of industrial pollution and emissions reduction, and the National Development and Reform Commission, Ministry of Transportand Ministry of Construction are also involved," Ma said.

According to Chen, in Atmospheric Pollution Prevention and Control Law, the Ministry of Environmental Protection only accounts for one-third of the responsibilities.

"Clarifying the duty of different departments to better implement the law is the emphasis of our work," Chen said.

Experts say the weak enforcement of the environmental protection law in some cases is mainly due to local protection and intervention. "The major sources of pollution not only need to be monitored 24 hours, but the results should be publicized in real time as well," Ma said.